Abstract Insect galls of the Floresta da Cicuta (Volta Redonda, RJ, Brazil). Galls are changes in the pattern of growth and development of plant tissues or organs in response to the action of an inducing organism, usually an insect. The goal of the present study was to inventory the insect galls of the Floresta da Cicuta (Volta Redonda, RJ, Brazil). The collections were carried out along all the trails, totaling 16 hours of sampling. Forty-three morphotypes of insect galls were found in 24 plant species (18 genera and 15 families). Sapindaceae and Euphorbiaceae were the most richness host plant families. Six new records of host plant species are presented: Senefeldera verticillata (Vell.) Croizat. (Euphorbiaceae), Inga acuminata (Fabaceae), Ocotea elegans (Lauraceae), Ouratea stipulata (Ochnaceae), Psychotria nuda (Rubiaceae) and Cestrum intermedium (Solanaceae). Most of the galls occurred on leaves (n = 21) and stems (n = 18), followed by buds (n = 2), two gall morphotypes occurred simultaneously on leaves and stems. One-chambered galls were more frequent (n = 31), as well as glabrous galls (n = 33). The gallers belong to three insect orders: Diptera (Cecidomyiidae), Hemiptera, and Lepidoptera. The associated fauna comprised parasitoids (Hymenoptera), inquilines (Hemiptera and Coleoptera) and successors (Isoptera and Acari).